The disclosure is directed to an adjustable key wrench. Specifically, the disclosure is directed to a self-adjusting key wrench.
Conventional adjustable wrenches typically comprise a movable jaw and a stationary jaw extending from a handle portion. A worm gear receiving portion is provided at a lower portion of the movable body. A square hole is disposed in the fixed jaw to receive a section of the worm gear receiving portion of the movable jaw. A worm gear is provided within the square hole to engage the worm gear receiving portion of the movable jaw. When a user manually rotates the worm gear, the movable jaw can move in a horizontal direction corresponding to the rotation of the worm gear, which in turn drives the movable jaw to move in the same direction, thereby adjusting the width of a jaw of the wrench.
Adjustable wrenches having that configuration are relatively simple in construction and convenient for use. However, such a wrench has disadvantages that when the width required to be adjusted is relatively large, the worm gear must be turned frequently. For example, if a large size wrench is used in exploitation of oil where a relatively larger pipe or nut needs to be turned, it is necessary to turn the worm repeatedly to give a full jaw travel. Furthermore, it is difficult to reliably hold an object by manually adjusting the width of the jaw. Also, adjusting the gap may become cumbersome when the variability of the widths needed to be adjusted is large and frequent.
Accordingly, there is a need for a fast, self-adjusting wrench, capable of adjusting to the width of the nut with one hand, while maintaining the width for the duration of the operation of the wrench.